[NatureNS] Correction; Fw: Velocity of light

From: David & Alison Webster <dwebster@glinx.com>
To: naturens@chebucto.ns.ca
References: <5A9443B08B714115A5AAA3DA875A05EB@D58WQPH1>
Date: Sat, 22 Sep 2012 09:58:12 -0300
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Hi Fred & All,                    Sept 22, 2012
    Explanations of weight/mass usually resemble inconsistent confessions 
obtained by torture but I guess that is ok now.

    It seems logical to me that weight should be treated as a special case 
of F=ma where a in this case is g and F is measured by exerting an equal and 
opposite force upward to keep the mass from falling.

    One could then determine the magnitude of mass as F/g and then proceed 
to work out units of momentum, inertia etc from there.

    But unfortunately kg has been defined (or perhaps redefined) as a unit 
of mass which leads to everything being a hopeless muddle.

    I would try to reform the system of units dealing with weight, mass and 
distance but I am tied up this afternoon.

Yt, Dave Webster, Kentville
----- Original Message ----- 
From: "Fred Schueler" <bckcdb@istar.ca>
To: <naturens@chebucto.ns.ca>
Sent: Friday, September 21, 2012 9:19 PM
Subject: Re: [NatureNS] Correction; Fw: Velocity of light


> Quoting David & Alison Webster <dwebster@glinx.com>:
>
>> I just dug out my 1st yr Physics (Weber, White & Manning, 1952) and  they 
>> consistently refer to 'speed of light' as opposed to 'velocity  of 
>> light'. Four other sources (1941, 1948, ~1965 &1962) have velocity.
>
> * indeed, it would be ineffective to purge society, or even  literature, 
> of all who misuse speed/velocity or weight/mass. Or, to  bring it closer 
> to natural history, all who refer to nonhemipterans as  "bugs."
>
> fred.
> ===============================================
>
>> ----- Original Message ----- From: "David & Alison Webster" 
>> <dwebster@glinx.com>
>> To: <NatureNS@chebucto.ns.ca>
>> Sent: Friday, September 21, 2012 7:44 PM
>> Subject: Velocity of light
>>
>>
>>> Dear All,                        Sept 21, 2012
>>>   The recent discussion about transmission of electricity, reading  of 
>>> HEAT and reading some of Energy... brings to the forefront a  question 
>>> that has nagged me for decades. Perhaps someone can clarify.
>>>
>>>   In the typical elementary physics text we are told that velocity  is a 
>>> vector quantity, and to quote one text "velocity... may be  defined as 
>>> the rate of change of position in a given direction".  But "In cases 
>>> where the direction of motion does not require to be  considered , the 
>>> term speed is employed to express the rate of  travelling."
>>>
>>>   Based on the above I would think that the rate of movement of  light 
>>> should be called speed, i.e. speed of light but I think it is  always 
>>> called velocity.
>>> For example, if light from the sun is reflected from two 45o  mirrors 
>>> then a beam of light could be directed from the earth back  to the sun 
>>> and, the velocity would then be minus 3 x 10^10 cm/sec.  Or if variously 
>>> scattered or reflected then the velocity, relative  to the initial sun 
>>> to earth direction, would always be less than 3  X 10^10 and after 
>>> several reflections might be zero.
>>>
>>>   Is there some good reason why the speed of light is termed  velocity 
>>> of light ? Or is it called velocity because the textbook  authors forget 
>>> what they said in chapter one by the time they write  chaper eleven ? 
>>> (And they all copy from each other)
>>> Yt, Dave Webster, Kentville
>>
>>
>
>
>
> ------------------------------------------------------------
>          Frederick W. Schueler & Aleta Karstad
> Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
> Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
> Daily Paintings - http://karstaddailypaintings.blogspot.com/
>          South Nation Basin Art & Science Book
>          http://pinicola.ca/books/SNR_book.htm
>     RR#2 Bishops Mills, Ontario, Canada K0G 1T0
>    presently in Cochrane  - 49.06274N 81.02415W -
>            on the great Ontario Claybelt
>    (613)299-3107 <bckcdb at istar.ca> http://pinicola.ca/
> ------------------------------------------------------------
>
>
>
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